How much HP from 2 deleted cats?
Thread Starter
Safety Car
Joined: Apr 2008
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From: NJ
2025 C8 of the Year Finalist - Modified
2023 C8 of the Year Finalist - Unmodified
2022 C7 of the Year Finalist - Modified
2021 C7 of the Year Finalist - Unmodified
How much HP from 2 deleted cats?
To the rear wheels... that is.. just curious. 2-3 maybe? 
Melting Slicks
Joined: Jun 2007
Posts: 2,704
Likes: 4
From: Lone Star State
I agree with the top. Pro/Cons
Pro:
Weight reduction
MAYBE 3-5 hp
Louder exhaust note
Cons:
You wont pass inspection
If they (the law) catches you...huge fine (google it)
The exhaust smell is horrible
Pro:
Weight reduction
MAYBE 3-5 hp
Louder exhaust note
Cons:
You wont pass inspection
If they (the law) catches you...huge fine (google it)
The exhaust smell is horrible
Thread Starter
Safety Car
Joined: Apr 2008
Posts: 4,835
Likes: 1,850
From: NJ
2025 C8 of the Year Finalist - Modified
2023 C8 of the Year Finalist - Unmodified
2022 C7 of the Year Finalist - Modified
2021 C7 of the Year Finalist - Unmodified
Thanks guys. I have high flow cats already (along w/headers and B&B's). The car already stinks pretty bad on start-up until the cats heat up, so I can't imagine no cats at all. Was more interested in seeing what gains could be had, if any. Thanks for the comments/suggestions. 
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Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
It does!! The chamber that you end up with after busting out the core causes turbulence in the pipe and you loose valuable exhaust scavenging thus reducing power. If you want more power, get a set of headers and high flow cats.
Banned Scam/Spammer
Joined: May 2007
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From: Machineguns, because I don’t compromise
Bill, I respect your opinion as do most here... I will say, that just like many topics on this forum (and other forums) there are always countering opinions for the same topic depending on which thread you're in.
I've heard that the chamber of a pup cat is a pressurized cylinder with the engine running and turbulence due to physics isn't to the level of what you're saying in your post.... in fact it's very minor and is a non-issue.
Again, there are two sides to each coin.
I don't know which one is correct, but there is a 14% reduction in backpressure from the 2 cat pipes ('02+) compared to my 4 catted '01.... -on the cheap, if adding a 224 cam, I think I'll take the "risk" of a little turbulence (if true) for the trade of 14% reduction in backpressure.
Peace.
I've heard that the chamber of a pup cat is a pressurized cylinder with the engine running and turbulence due to physics isn't to the level of what you're saying in your post.... in fact it's very minor and is a non-issue.
Again, there are two sides to each coin.
I don't know which one is correct, but there is a 14% reduction in backpressure from the 2 cat pipes ('02+) compared to my 4 catted '01.... -on the cheap, if adding a 224 cam, I think I'll take the "risk" of a little turbulence (if true) for the trade of 14% reduction in backpressure.
Peace.
Race Director
Joined: Dec 2004
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From: Haymarket VA
Race Director
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From: Texas Hill Country
If we are talking about stock engines or bolt ons I would def keep the cats. If we are talking about boost, high RPMs, bigger power then the cats will restrict quite a bit. heads/cam will be fine with hfc's but big cubes, etc should toss em.
Pro
Joined: Apr 2007
Posts: 585
Likes: 2
Gutting the pup cats is a no-no on Corvettes.In general, I'd be surprised if people around here would see even a one horsepower gain by removing the cats on their stock Corvettes. (I'll concede that the results might be different on a non-stock car.) The smells, destruction of the environment, and inspection laws make removing cats in the quest for horsepower a downright stupid choice.
Besides ... "Give a hoot! Don't pollute!"
LO PHAT
Race Director
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From: Haymarket VA
I still have hi-flow cats....
Last edited by WKMCD; Aug 26, 2010 at 05:51 PM.
Race Director
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From: Texas Hill Country